At present, there are two general methods used for measuring the heartbeat rate of exercisers when using sport equipments for the exercise. One method detects the change of blood density in the human skin for the pulse measurement, and the other method detects the potential signal produced by the weak amplitude of vibration of the current, which is the so-called bio-potential signal for the pulse measurement. For the method using the change of blood density in the exerciser's skin for the pulse measurement, a device such as a clamp or a bracelet is generally used to be fixed onto the exerciser's body. However, the device using a clamp or a bracelet is movable and thus the electric wire may be exposed partially. The device will be moved and the electric wire will be shaken or twisted when the exerciser is doing exercises. The displacement of the device and the interference of the conductive wire according to the foregoing phenomenon directly affect the computation for measuring the heartbeat rate with respect to the microprocessor of the system, so that the measured value of the heartbeat rate may be inaccurate and results in a large error. In the meantime, the conductive wire also affects the direction or is in the way of the of the exerciser's movement.
Further, a bio-potential signal is used for the pulse measurement by directly putting an electrode sensor of the fitness equipment in contact with the human body, so that the conductive wire will not vibrate and thus overcoming the shortcoming of causing interferences. Since the current bio-potential signal measuring device (as shown in FIG. 1) requires two electrode sensors, which are a pair of corresponding sets including a first active sensor electrode 10a with a first common point sensor electrode 10b and a second active sensor electrode 10d with a second common point sensor electrode 10c (wherein the foregoing first common point sensor electrode 10b and the second common point sensor electrode 10c are connected together to form the same potential). The two sets of electrode sensors are connected to a pulse measurement device 10 by a conductive wire 101, 102, 103, 104, and the pulse measurement device 10 comprises a bio-potential detector 11 connected to the foregoing two sets of electrode sensors, a bio-signal measurement 12 for receiving the signal transmitted from the bio-potential sensor 11, an analog filter/amplifier 13 for receiving the signal transmitted from the bio-signal measurement 12, and an associative processing unit 14 for receiving the signal processed by the analog filter/amplifier unit 13 for the processing or comparison of related settings, a signal processing unit 15 for processing the signal and displaying a pulse data on a display device 17 and also feeding back the signal to the associative processing unit 14 for the interactive processing. Further, the associative processing unit 14 can be connected to an external input device 16 for entering data or related settings.
Although the foregoing device does not have shaking conductive wires anymore and can overcome the shortcoming of having interferences, each of the two sets of electrode sensors at the gripping positions of the left and right hands should have a first active sensor electrode 10a and a first common point sensor electrode 10b (a second active sensor electrode 10d and a second common point sensor electrode 10c). A user has to hold the first active sensor electrode 10a and the first common point sensor electrode 10b with one hand and the second active sensor electrode 10d and the second common point sensor electrode 10c with the other hand for its use, so that the user's bio-potential is detected by the first active sensor electrode 10a and the first common point sensor electrode 10b (or the second active sensor electrode 10d and the second common point sensor electrode 10c) through the user's hand. However, a hand is holding the first active sensor electrode 10a and the first common point sensor electrode 10b (or the second active sensor electrode 10d and the second common point sensor electrode 10c), and it will reduce the contact area of the electrode sensor and affect the reliability of receiving the signals. Therefore, when a user is doing exercise, the user may have small hands or wants to change gestures or is afraid of not able to grip the first active sensor electrode 10a and the first common point sensor electrode 10b (or the second active electrode sensor 10d and the second common point sensor 10c) at the same time, it will affect the measured value of the pulse.